U.S. patent number 4,482,938 [Application Number 06/412,179] was granted by the patent office on 1984-11-13 for electrical apparatus with plug-in modules.
Invention is credited to Alexander R. Norden.
United States Patent |
4,482,938 |
Norden |
November 13, 1984 |
Electrical apparatus with plug-in modules
Abstract
The disclosed apparatus involves circuit modules paired with
companion terminal assemblies alongside each other in an enclosure.
The circuit modules are operable along front-to-back paths for
installation in the enclosure and removal. The terminal assemblies
are also operable along front-to-back paths but at a slant angle to
the paths of the circuit modules. The sides of each circuit module
and its companion terminal assembly have mating contacts that are
in engagement in the operative condition of the terminal assembly
and the adjacent circuit module. As a terminal assembly is moved
forward or raised from its installed or operative condition, its
contacts have a sidewise component of movement that carry them out
of the paths of the module contacts, so that the module can be
removed and installed with ease. The apparatus can be wired from
the front when each terminal assembly is in its raised condition.
Interlock means enforces certain sequential operations of the
circuit modules and the terminal assemblies.
Inventors: |
Norden; Alexander R. (New York,
NY) |
Family
ID: |
23631921 |
Appl.
No.: |
06/412,179 |
Filed: |
August 27, 1982 |
Current U.S.
Class: |
361/823; 361/732;
361/801; 439/131; 439/368; 439/43; 439/61; 439/660 |
Current CPC
Class: |
H05K
7/10 (20130101); H05K 7/1474 (20130101); H05K
7/1469 (20130101); H05K 7/1467 (20130101) |
Current International
Class: |
H05K
7/10 (20060101); H05K 7/14 (20060101); H05K
007/10 () |
Field of
Search: |
;339/18R,18B,65,66R
;179/91R,98 ;361/338-340,390,391,393-395,415,425,426 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Tolin; G. P.
Claims
What is claimed is:
1. Electrical apparatus including an enclosure, at least one
circuit module adapted to be inserted and removed from the
enclosure, said circuit module and said enclosure having
cooperating first guide means for constraining the circuit module
to move along a prescribed in-and-out path for installation in the
enclosure and removal, said circuit module having a plurality of
module contacts at a side thereof, and a terminal assembly having a
plurality of companion contacts at a side thereof disposed for
mating with said module contacts, respectively, said apparatus
having second guide means for constraining said terminal assembly
to be moved along an in-and-out path that slants at an acute angle
to the in-and-out movement of said circuit module such that, when
the circuit module and the terminal assembly are in their operative
positions, the module contacts are engaged by said companion
contacts of the terminal assembly and, as said terminal assembly is
drawn from its operative position outward along said slant angle,
it attains a forward position wherein its companion contacts are
separated from said module contacts and the circuit module can be
removed from the enclosure and/or installed therein along its
in-and-out path without engagement of the module contacts with the
terminal assembly contacts.
2. Electrical apparatus in claim 1 wherein each mating pair of
contacts comprising one of said module contacts and one of said
companion contacts of the terminal assembly comprises a gripped
contact and a pair of spaced-apart resilient contact elements
arranged to have sliding and gripping contact with said gripped
contact during the in-and-out movement of the terminal
assembly.
3. Apparatus as in either claim 1 or 2 wherein said circuit module
and said terminal assembly include cooperating formations
constituting at least part of said second guide means and located
adjacent the module contacts and the companion contacts for guiding
said contacts into mutual sliding contact as aforesaid and for
drawing said side of said terminal assembly toward said side of the
circuit module as the terminal assembly is moved toward its
operating position.
4. Apparatus as in either claim 1 or 2 wherein said enclosure and
said terminal assembly have cooperating formations comprising at
least part of said second guide means for enforcing in-and-out
movement of said terminal assembly along its slant path.
5. Apparatus as in either claim 1 or 2 wherein said enclosure and
said terminal assembly have cooperating formations comprising part
of said second guide means for enforcing in-and-out movement of
said terminal assembly along its slant path, and wherein said
circuit module and said terminal assembly also include cooperating
formations constituting part of said second guide means and located
adjacent the module contacts and the companion contacts for guiding
said contacts into mutual sliding contact as aforesaid and for
drawing said side of said terminal assembly toward said side of the
circuit module as the terminal assembly is moved toward its
operating position.
6. Electrical apparatus as in claim 1 wherein a portion of said
terminal assembly obstructs the circuit module against being moved
outward when the circuit module and the terminal assembly are in
their operative positions, the obstructing portion of the terminal
assembly being out of the in-and-out path of the circuit module
when the terminal assembly has been moved along said slant angle
into said forward position thereof, whereby the obstructing portion
of the terminal assembly when in its operative position also
obstructs the path of insertion of a circuit module.
7. Electrical apparatus as in claim 6, further including an
interlock operable between a first position arresting said terminal
assembly in its operative position and a second position wherein
the terminal assembly is free for outward movement, whereby said
interlock when in said first position is also effective to prevent
removal of said circuit module from its installed position.
8. Electrical apparatus as in either claim 1 or 6 including an
interlock operable between a first position for arresting said
terminal assembly in said forward position and a second position
releasing the terminal assembly for in-and-out movement, said
terminal assembly having screw terminals extending from said
companion terminals, said screw terminals being accessible for
wiring in the forward position of the terminal assembly.
9. Electrical apparatus as in claim 6, further including an
interlock operable between a first position arresting said terminal
assembly in its operative position and a second position wherein
the terminal assembly is free for outward movement, whereby said
interlock when in said first position is also effective to prevent
removal of said circuit module from its installed position, said
interlock when in its second position blocking the in-and-out path
of a circuit module against insertion of a circuit module and
against removal of an installed circuit module.
10. Electrical apparatus as in claim 1 or 2, further including an
interlock operable into a first position in which it cooperates
with said terminal assembly to prevent its movement out of either
said operative position or said forward position, said interlock
also being operable into a second position wherein said terminal
assembly prevents movement of the interlock to its first position
unless the terminal assembly is in either its operative position or
its forward position.
11. Electrical apparatus including an enclosure, at least one
circuit module adapted to be installed in said enclosure and
removed therefrom via the front of the enclosure and having a
plurality of contacts at a side thereof, said enclosure having
first guide means for constraining the circuit module to move along
a prescribed path during installation and removal, a terminal
assembly alongside said circuit module in their operative positions
in the enclosure, said terminal assembly having a plurality of
companion contacts releasably mating with said circuit module
contacts in said operative positions and being accessible from the
front of the enclosure and movable forward of the circuit module
while the latter remains fully installed, second guide means for
constraining said terminal assembly to move bodily between said
operative position and a position projecting forward of said
circuit module when the latter is in its operating position, said
terminal assembly including plural screw terminals accessible for
wiring while the terminal assembly is in its forward position,
means for connecting at least some of said screw terminals to said
circuit module, and releasable means for holding said terminal
assembly stably in its forward position to facilitate wiring the
screw terminals.
12. Electrical apparatus as in claim 11 wherein said releasable
holding means is also selectively cooperable with said terminal
assembly for holding the latter in its operative position.
13. Electrical apparatus as in claim 12 wherein said releasable
holding means is movable to a release position wherein the terminal
assembly is movable between its operative position and its forward
position and wherein said releasable holding means when in said
release position obstructs said prescribed path of the circuit
module so as to prevent removal of an installed circuit module and
to prevent installation of a circuit module, said terminal assembly
additionally having a portion blocking removal of an installed
circuit module and insertion of a circuit module while said
terminal assembly is in its operative position, whereby said
releasable holding means is indirectly effective for blocking
insertion and removal of a circuit module while the releasable
holding means retains the terminal assembly in its operative
position.
14. Electrical apparatus as in claim 1 wherein said enclosure has
stationary plug-in contacts and said circuit module has plug-in
contacts that mate with said stationary plug-in contacts when the
circuit module is fully inserted into the enclosure.
15. Electrical apparatus as in claims 1 or 14 including additional
circuit modules and terminal assemblies all as aforesaid,
alternating in a row in close side-by-side assembly.
16. Electrical apparatus as in claim 1 wherein said terminal
assembly has wiring terminals that are accessible for attaching
wires thereto when the terminal assembly is in its forward position
and are accessible from the front of the apparatus for test when
said terminal assembly is in its operative position.
17. Electrical apparatus as in claim 11 or 16 wherein said terminal
assembly includes a wiring gutter movable as a unit therewith.
18. Electrical apparatus as in claim 10 wherein said interlock when
in said second position blocks the in-and-out path of the circuit
module.
19. Electrical apparatus as in claim 12 wherein said releasable
holding means includes a portion blocking the path of the circuit
module while the releasable means is in position releasing the
terminal assembly for in-and-out shift.
Description
The present invention relates to electrical apparatus having
circuit modules and companion terminal assemblies.
In a long established practice, circuit modules have been designed
to be removed from assembled electrical equipment and replaced
readily, as for repairing or altering the equipment. In particular,
the circuit modules may be part of a programmed control system that
responds to input signals (as from condition-sensing devices) and
provides operating control for diverse electromechanical equipment.
The system involves connections from the control modules to
external circuits of the controlled equipment. The modular
apparatus incorporates terminal assemblies for providing
connections from the control modules to signal input circuits, to
energizing supplies, and to controlled apparatus.
An object of this invention resides in improving modular electrical
apparatus having circuit modules and companion terminal assemblies.
More specifically, an object of the invention resides in providing
novel electrical apparatus having readily installed and replaced
circuit modules and companion terminal assemblies that provide
connection from the circuit modules to external circuits, wherein
the wiring of the terminal assemblies can be performed at the same
area (conveniently called the "front" of the apparatus) where the
circuit modules are displayed and at which the circuit modules are
accessible for installation and removal. A related object resides
in providing novel apparatus of this kind wherein circuit modules
and companion terminal assemblies are compactly assembled and
utilize the front area of the apparatus efficiently.
A further object of the invention resides in providing a novel
assembly of circuit modules and companion terminal assemblies that
have mating contacts wherein the terminal assemblies can be wired,
manipulated readily and tested, even though access may be limited
to the front of the apparatus.
A further object resides in providing novel assembled modular
circuit apparatus wherein manipulation of terminal assemblies and
circuit modules is controlled and coordinated by interlocks that
ensure their sequential manipulations. This sequence of operations
may be devised for facilitating installation and removal of the
circuit modules, or for foreclosing possible damage to one another,
or both, and for facilitating wiring of the terminal assemblies. A
further object resides in providing novel interlock means for the
foregoing purposes and for retaining the circuit modules securely
in their operative positions.
These and other objects are achieved in the illustrative modular
assembly described below and shown in the accompanying drawings.
Briefly, circuit modules and companion terminal assemblies adjacent
the circuit modules are assembled in an enclosure, such that the
circuit modules can be installed and removed from the "front" of
the electrical apparatus. The terminal assemblies can be
manipulated for connecting them to the circuit modules and
disconnecting them, and for wiring them, all such manipulations
being performed at the front of the assembly.
The circuit modules are guided for movement along parallel paths
into and out of the assembly at its front. Each terminal assembly
is also operable along a controlled path between a "forward" or
"raised" position wherein it is disconnected from its companion
circuit module and an "operating" position wherein each installed
circuit module and its companion terminal assembly are connected by
mating contacts. The terminal assembly is guided for movement along
a path that is at a slant angle to the in-and-out path of its
companion circuit module, such that the terminal assembly has a
component of motion laterally away from its companion circuit
module as it is moved to its forward or raised position from its
operating position. In moving the terminal assembly forward, its
contacts are parted from mating contacts of the installed companion
circuit module. Additionally, due to the "slant angle" of the
terminal assembly's path relative to that of the circuit module,
the lateral shift of the entire terminal assembly frees the circuit
module to be moved along its prescribed path. With the terminal
assembly raised, in-and-out movement of the circuit module is
unobstructed and unimpeded. While a circuit module is being moved
in or out, the contacts of the companion terminal assembly remain
in positions having clearance from the corresponding contacts of
the circuit module being moved in or out. Consequently, there is no
concern for damage being caused to the companion contacts of the
circuit module and the terminal assembly during their in-and-out
shifts, nor is there danger of damage to circuits due to random
engagement of some module contacts with corresponding contacts of a
terminal assembly that is only partly raised.
Ordinarily the circuit modules have their own plug-in contacts for
engaging and disengagement from companion contacts in the
apparatus. The circuit module commonly has "edge" contacts on a
printed circuit board. In-and-out movement of the circuit module is
facilitated by providing each circuit module and its terminal
assembly with mating contacts that remain disengaged and mutually
non-interfering during the in-and-out movement of the circuit
module. A terminal assembly that is "raised" can be moved "in" to
its operating position while the circuit module is installed in its
operating position, their related contacts becoming engaged during
this operation.
As a separate feature, the terminal assemblies have terminals that
are accessible from the front of the assembly for test purposes.
Further, the terminal assemblies have terminals that can be readily
wired from the front of the apparatus while the terminal assembly
is in its forward or raised position. Detents are provided for
holding the terminal assemblies raised securely to facilitate
wiring.
As a further and separate feature, interlock means is provided for
several purposes. In the illustrative apparatus detailed below, the
control modules are held securely in operative position by the
companion terminal assemblies, and an interlock slide in one
position retains the terminal assemblies in their operative
position. Thus the circuit modules and the terminal assemblies are
jointly secured in their operative positions. When the interlock
slide is shifted, each released terminal assembly can be raised out
of its operative position. When this is done, a circuit module is
no longer retained in its operative position by its companion
terminal assembly. However, when the interlock slide releases the
terminal assemblies so that they can be raised, the interlock side
shifts so as to maintain the circuit modules locked in their
operative positions. Only when a terminal assembly has been shifted
fully to its raised position can the interlock slide be shifted to
lock the shifted terminal assembly in its forward position. Its
companion circuit module can then be removed since it is no longer
detained either by its companion terminal assembly or by the
interlock slide.
By like token, a circuit module can be inserted only while its
companion terminal assembly is held by the interlock slide in its
fully raised position. A circuit module cannot be inserted when its
companion terminal assembly is in its operative position because
the terminal assembly obstructs the insertion path of the circuit
module. The interlock slide must first be shifted to release the
companion terminal assembly and in that condition the interlock
slide obstructs installation of a circuit module. Only when the
terminal assembly has been fully raised and the interlock slide has
been shifted to lock the terminal assembly in its fully raised
position can a circuit module be installed.
Because of the interlock, a terminal assembly must be secured in
such a position as not to interfere with the free fore-and-aft
movement of its companion circuit module. This feature is of
particular benefit where the circuit module has its own plug-in
contacts, and where the terminal assembly has contacts that move
into secure engagement with mating contacts of its companion
circuit module. When the circuit module is unencumbered by
engagement of its contacts with the mating contacts of the terminal
assembly, it is relatively easily manipulated for removal and for
installation. In a separate operation, the terminal assembly can be
moved from its fully raised position to its operative position only
when a circuit module has been installed fully, or when it has been
removed. Faulty and potentially damaging manipulations are
forestalled.
In its full detail, the interlock system thus provides unique
benefits. Less than the whole system also imparts certain benefits.
For example, the interlock slide remains available when needed for
locking a selected terminal assembly "raised" and with its screw
terminal in easy access for insertion of a wire and for securing
the wire in place. By virtue of this feature, the assembled
apparatus can be wired even when access is limited to the front of
the apparatus. It is at this front of the apparatus that the
circuit modules commonly have display indicia and signal lights.
Quite apart from the lights and indicia, it is at the front of the
apparatus where access is afforded for removal and installation of
the circuit modules. The terminal assemblies of the illustrative
apparatus also provide access at the "front" for test purposes and
for wiring.
The interlock guards against a further dangerous condition. When
the terminal assembly is fully raised, its contacts have shifted
laterally into clearance positions safely out of the in-and-out
paths of the circuit module's mating contacts. It may be imagined
that a terminal assembly is raised only partway to its raised
position so that its contacts have moved laterally only partway to
their clearance positions. A circuit module might then be inserted
and moved to its fully installed position. During that movement,
some of the contacts of the circuit module might, at random, brush
against mating contacts of the terminal assembly. The resulting
unpredicted connections to only some of the module's contacts could
cause circuit damage. The interlock forestalls that condition by
insuring shift of each terminal assembly to its fully raised
position, thus insuring full lateral shift of its contacts into
their clearance positions before the circuit module can be
inserted.
The nature of the invention in its various aspects, and its further
novel features and advantages, will be better appreciated from the
following detailed description of an illustrative embodiment and
from the accompanying drawings forming part of the disclosure of
the illustrative embodiment.
In the drawings:
FIG. 1 is a fragmentary front view of an illustrative embodiment of
the invention in its various aspects;
FIG. 2 is a fragmentary elevation of the illustrative embodiment,
partially in cross-section, at the plane 2--2 in FIG. 1;
FIG. 3 is a fragmentary elevation of components of the illustrative
embodiment, viewed as in FIG. 2 and shown partly in
cross-section;
FIG. 3A is a fragmentary cross-section of the illustrative
embodiment at the plane 3A--3A in FIG. 2;
FIG. 4 is a fragmentary cross-section of the illustrative
embodiment at the plane 4--4 in FIG. 1;
FIG. 5 is a fragmentary perspective of a wiring gutter, being a
component of the apparatus shown in FIGS. 1 and 2;
FIG. 6 is a fragmentary view corresponding to FIG. 2, partly in
cross-section, drawn to larger scale than FIG. 2;
FIG. 7 is a fragmentary detail of one of the plug-in modules
(components of the illustrative embodiment) as viewed from the
right of FIG. 6;
FIG. 8 is a fragmentary detail of one of the terminal assemblies in
FIGS. 1, 2 and 6 as viewed from the left of FIG. 6, drawn to larger
scale than FIG. 6;
FIG. 9 is a fragmentary cross-section at the plane 9--9 in FIG.
8;
FIG. 10 is a fragmentary cross-section of mating contacts, being
parts shown severally in FIGS. 7 and 8, as viewed at the plane 9--9
in FIG. 8;
FIG. 11 is a fragmentary view of a typical contact of the terminal
assembly, the contact being an element in FIG. 8 but drawn to
larger scale;
FIG. 12 is a fragmentary cross-section of a contact shown in FIG.
11 at the plane 12--12 therein;
FIGS. 13 and 14 are cross-sections of the contact of FIG. 11 at the
planes 13--13 and 14--14 therein.
Referring to the drawings, an enclosure 10 is shown containing a
series of plug-in circuit or programmable control modules 12 and a
series of terminal assemblies 14. Most of the terminal assemblies
are shown in their plugged-in positions, but terminal assembly 14A
is shown in its un-plugged position, raised in FIGS. 2 and 6.
Each control module 12 has a handle 16, enabling the module to be
pulled away from the front of the apparatus, upward as viewed in
FIG. 2. Elongated guides 18 are struck out of walls 20 of the
enclosure. These guides cooperate with the circuit modules 12 to
determine the paths of the modules when being installed in and
removed from the enclosure. Each module has a printed-circuit board
22 (FIGS. 6 and 7) bearing edge contacts that are received and
gripped between respective resilient pairs of plug-in contacts 24
of a so-called "mother" board at the back of the enclosure. Control
signals as from programming circuits and sensing devices are
impressed on the control modules via contacts 24, and these
contacts serve also to interconnect the control modules.
The front face of each circuit module 12 has a window 26. Indicia
on the window and indicating lamps behind selected ones of the
indicia are aligned with respective contacts 28 (FIG. 7) on
printed-circuit board 22.
Controlled currents can be conducted by the terminal contacts 28 of
each module, optionally through fuses 30. The current capacity of
contacts 28 is high, e.g. up to 10 Amperes, compared to the low
signal currents at the edge contacts of the printed circuit boards
22 engaged by contacts 24.
A screw-terminal 32 in each assembly 14 is provided for each of the
contacts 28 of its companion plug-in control module 12. Indicia
and/or a lamp of module 12 is opposite some terminals 32 of the
terminal assembly. Each screw terminal includes a four-sided collar
34 of sheet metal having a bottom with a lateral depending lip 34a
(FIG. 6). At its top, collar 34 has a double-thickness wall 34b
that is screw-threaded and receives a screw 35. As seen in FIGS. 6,
8 and 10-14, each screw terminal 32 includes a one-piece contact
element 36 comprising a double-thickness top portion 36a that
extends into and across collar 34, an elongated connecting spine
36b, and a pair of resilient contacts 36c. These contacts are
spaced narrowly from each other. Upstanding portions 36d are spaced
farther apart than contact pairs 36c, portions 36c and 36d being
connected by sloping ramps.
Each element 36 is suitably anchored in a body 38 of molded
electrical insulation. With the terminal assembly 14 raised (see
terminal assembly 14A in FIG. 6) an external circuit wire is
inserted in the opening (at the right, FIG. 6) below portion 36a
and above the bottom of collar 34. After a wire has been inserted,
screw 35 is tightened against contact portion 36a to draw collar 34
up and clamp the inserted wire against contact portion 36a. The
wire is bent into and along a wiring gutter, described below.
Each plug-in module has a series of fixed posts 40 (which may be
shouldered rivets) spaced apart in a row parallel to contacts 28.
Only one such post appears in FIGS. 6 and 7. One such post is also
shown in phantom in FIGS. 8 and 9. For each post, insulating body
38 has a pair of parallel spaced shoulders or ramps 42 terminating
at overhang 42a. The lower surface of post-head 40a coacts with
ramps 42 and overhang 42a. As terminal assembly 14A is depressed,
body 38 is constrained by posts 40 to guide its pairs of resilient
contacts 36c into aligned sliding, gripping contact with respective
module contacts 28. Posts 40 also pull insulating body 38 and its
contact pairs toward the printed circuit board 22 and its contacts
28. This provision thus assures proper mating of contacts 28 and
36c despite possible warping and other dimensional variations of
parts 22 and 38. Terminal assembly 14 comprises two elongated
molded parts 38 each of which contains ten screw terminals 32 in
this example. The two molded parts 38 are united by wiring gutter
44. The wiring gutter (here of metal) extends along the whole
length of its terminal assembly, uniting the bodies 38. Wiring
gutter 44 is fixed to each insulating body 38, conveniently by
screws (not shown). One or each of the opposite pair of sheet-metal
walls 20 of enclosure 10 (see FIGS. 2, 3 and 6) has an aperture
opposite to the wiring gutter of each terminal assembly 14. Wiring
from screw terminals 32 is trained along wiring gutter 44 and
extends through grommets 46 in wall(s) 20. Opening 46a provided by
each grommet is in alignment with its related wiring gutter both
when the terminal assembly is raised and when it is depressed into
its operative position.
As seen in FIG. 5, the wiring gutter has an off-set rail 44a (one
at each end) and the opposite walls 20 of the enclosure have slots
48 for all those rails (e.g. slots 48 in FIGS. 3 and 6) that
constrain the in-and-out movement of the terminal assembly to
follow a path which, here, is at a 10.degree. angle in relation to
the in-and-out path of the plug-in modules 12 along their guides 18
(FIG. 3). The side walls of the wiring gutter, as well as the sides
of the opening 46a of each grommet 46, extend along this same
angle. Manual effort is applied to upstanding handle 38a, for
forcing plug-in terminal assembly in and out. Each handle 38a
extends all along its body 38.
Rails 44a (FIG. 5) and the end-wall slots 48 provide rugged guiding
means that is effective to absorb the main stresses during the
plug-in and unplugging operations of the terminal assembly 14. As
indicated above, each post 40 cooperates with ramps 42 and overhang
42a of body 38 of the terminal assembly for assuring accurate
coaction between the resilient contact pairs 36c and module
contacts 28. The terminal-assembly contacts 36c have a small
component of motion toward and away from printed-circuit board 22
during in-and-out manipulation of the terminal assembly, and
contacts 36c have a major component of motion parallel to the face
of the printed-circuit board. Resilient contacts could be provided
facing board 22, replacing contact pairs 36c, for engaging the
right-hand ends (see FIG. 10) of contacts 28. However, the
described form of contacts 36c is advantageous as being essentially
independent of anticipated dimensional irregularities of board 22
and molded part 38, such as possible warping noted above.
As best seen at the left in FIG. 6, lateral ribs 38b extend along
nearly all of terminal assembly 14 and overlie plug-in module 12
when the terminal assembly is plugged in. When the terminal
assembly is pulled out (as represented at the right in FIG. 6) the
slant angle of movement enforced by rails 44a and cooperating slots
48 serves to shift rib 38b a short distance to the right. This is
enough to remove rib 38b from the plug-in and removal path of
module 12 as constrained by its guides 18. Therefore each module 12
can be plugged-in and removed only while its companion terminal
assembly 14 is in its raised position.
While terminal assembly 14 is being raised or pulled up, contacts
36c disengage module contacts 28. In this operation, contacts 36c
also shift away from the plane of printed-circuit board 22 due to
the slant path of terminal assembly 14. Thus contacts 28 become
unencumbered and have a free path for inward and outward shift of
circuit module 12 without being impeded by engagement of contacts
36c with module contacts 28. This attribute makes it easy to insert
and remove modules 12. Were contacts 36c in the path of contacts 28
during insertion of a module 12, much greater effort would be
needed. This is especially true where, as here, each of the many
contact pairs 28/36c is proportioned for relatively firm contact
pressure and high current.
Screw terminals 32 are accessible for test purposes from the
"front", i.e., at the same face as the display window 26. The
apparatus can also be wired from the front by raising the terminal
assemblies until the space between the bottom of each collar 34 and
contact portion 36a becomes accessible to receive the end of an
inserted wire. See assembly 14A, FIG. 6. Because the lower portion
of body 38 is relieved, an enlarged space develops between terminal
assembly 14A (raised) and the next-adjacent module 12 for training
wires along the wiring gutter. When the terminal assembly is
pressed down (at the left, FIG. 6) rib 38c lies adjacent to the
neighboring module 12 along nearly all of the module, to close the
front of the structure.
Each terminal assembly 14 has a protrusion 50 at each end. An
interlock 52 extends along each of two opposite walls 20 of
enclosure 10, opposite the ends of the terminal assemblies. As seen
at the top and the bottom of FIG. 1 and again in FIG. 2, fingers
52a (which extend integrally from slide 52b) can overlie or
underlie respective protrusions 50. In its overlying condition,
finger 52a locks a terminal assembly 14 in its fully plugged-in
position. In turn, portion 38b of that plugged-in and locked
terminal assembly serves to lock its companion module 12 in its
plugged-in condition.
In order to release any module 12 for removal, its companion
terminal assembly 14 must be raised. This can only be done by
shifting fingers 52a out of cooperation with terminal assemblies 14
so that fingers 52a overlie modules 12. Protrusions 50 prevent
fingers 52a from moving out of position overlying modules 12 until
a terminal assembly 14 being raised has been lifted to its fully
raised position (assembly 14A in FIG. 6) wherein contacts 36c of
the terminal assembly have been removed entirely from the paths
followed by module contacts 28 as the module is being removed or
installed. By like token, a module cannot be inserted while a
terminal assembly is partially raised because fingers 52a obstruct
the space where the module enters the enclosure, and protrusions 50
prevent fingers 52a from being shifted clear of the module path so
long as terminal assembly 14 is raised partway.
Fingers 52a of each interlock 52 extend integrally from a slide 52b
(FIGS. 3 and 4) that moves along the outside face of enclosure wall
20. Shouldered rivets 56 are fixed to wall 20 and move along slots
58 in slide 52b, for example. A finger piece 52c extending
integrally from slide 52b is operable to shift fingers 52a out of
or into the paths of protrusions 50. Any or all of terminal
assemblies 14 become free to be lifted, and the related plug-in
modules 12 can be freely inserted or removed only while interlock
fingers 52a overlie or underlie protrusions 50.
After a terminal strip has been fully raised and interlocks 52 have
been shifted so that their corresponding fingers 52a underlie
protrusions 50 of the raised terminal assembly, the terminal
assembly is locked against plugging-in movement. Screw terminals 32
can be loosened and tightened, without depressing the raised
terminal assembly. This provides for stability while work is being
done on the selected terminal assembly.
A circuit module cannot be removed while its terminal assembly is
in its operating position because rib 38b of the terminal assembly
overhangs the control module. Correspondingly, a control module
cannot be installed in the enclosure while its companion terminal
assembly is in its operating position because rib 38b then blocks
the path of insertion of the circuit module. The circuit modules
can only be removed or inserted when their companion terminal
assemblies are in a fully raised position in which the contacts of
the terminal assemblies have been shifted laterally out of the
in-and-out paths of companion or mating contacts of the circuit
module. Insertion and removal of circuit modules are thus
unencumbered by friction of the mating contacts, and there is no
danger of harm being caused to the resilient contacts of the
terminal assemblies by forcible insertion of a circuit module while
its companion terminal assembly is in its operative position, not
raised out of that position. Moreover, the interlock holds down a
circuit module while its companion terminal assembly is being
pulled forward.
The interlock also provides assurance that contacts 36c are located
safely out of the paths of contacts 28 which thus cannot touch
contacts 36c while module 12 is being inserted. If a module 12
could be inserted while its terminal assembly 14 is raised only
partway, certain contacts 28 at random might engage corresponding
contacts 36c during insertion of the module while other contacts
28/36c remain disengaged, due to dimensional disparities. Circuit
damage could occur. Engagement of contacts 28/36c during module
insertion is prevented by the interlock.
With access limited to the front of the enclosure, the user can
wire the terminal assemblies while they remain securely held in
position, and he can install and remove the circuit modules with
ease and in a manner that avoids damaging contacts of the terminal
assemblies. The entire front area of the enclosure can be utilized
by the circuit modules and their companion terminal assemblies.
Screw terminals 32 are shown exposed and accessible for tests that
may become useful from time to time. Of course these terminals can
be covered as by strips of insulation or by a bezel. Such
protective provisions do not negate the characteristic availability
of the terminals for test and for wiring and rewiring without need
for access to the side or rear of the assembled apparatus.
The foregoing represents the presently preferred embodiment of the
invention in its various aspects. As may be readily recognized,
certain of the novel features may be used without others for their
separate advantages and yet they are compatible and complementary.
Various modifications may be made by those skilled in the art.
Consequently the invention should be construed broadly in
accordance with its true spirit and scope.
* * * * *